Why can't I edit my personal scrapbook? It only has option to "View"

You add items to you're personal scrap book when you are actually editing pages.
e.g. If you want to add an autonav to the bottom of all your pages but edit it from a single location you could add a auto-nav block to your default page type - after adding it click it again and one of your options will be "Copy to Scrapbook" choose this then you can add it to your personal scrapbook.

Its worth noting that the scrapbooks are personal
Admin scrapbook is not available to Manager/user x
and vice-versa

Maybe its tied to that? all other scrapbooks are defined as Global.

Plus if you removed all your scrapbooks your copy to scrapbook would not work maybe its the core team preventing us from buggering up our installation by removing all scrapbooks this way we can be sure we always have one